Process and apparatus for chemical milling

ABSTRACT

An improved process for selectively etching a pattern into a base material by the photochemical method using a photoresist coating over the base material to enable the exposure of an etching solution to selected portions of the base material wherein the article to be etched is coated with the photoresist material and is thereafter continuously advanced and rotated at relatively uniform rates past a stationary spray of etching solution. A conveying system is also disclosed that is capable of simultaneously rotating and linearly advancing an article. The apparatus comprises a first and second spaced apart conveyor, the movable article carrier therebetween and in engagement with the conveyors and a driving means for each conveyor. The conveyors comprise a driving sprocket, an idler sprocket and an endless carriage in engagement with the sprockets. The endless carriage comprises a core and substantially equally spaced protrusions extending from each side of the core that engage the toothlike configuration of the periphery of each side of the sprockets. The carriages of each conveyor engages the article carrier to provide the linear movement. Differing the linear speeds or direction of travel of the two carriages enables variations in the rotational and linear movement of the article carrier.

ted States Patent 1191 Lagermasini et al.

[ Oct. 30, 1973 PROCESS AND APPARATUS FOR CHEMICAL MILLING [75] Inventors: Joseph P. Lagermasini, Towanda;

Leadom A. Warner, Sayre, both of Pa.

[73] Assignee: GTE Sylvania Incorporated, Seneca Falls, N.Y.

[22] Filed: Apr. 13, 1971 [21] Appl. No.: 133,525

Related US. Application Data [62] Division of Ser. No. 11,742, Feb. 16, 1970, Pat. No.

[56] References Cited UNITED STATES PATENTS 3,232,814 2/1966 Ruttan et al. 156/345 2,651,104 9 1953 Giros 29/148 Primary ExaminerJac0b H. Steinberg' Att0rney-Donald R. Castle [57] ABSTRACT An improved process for selectively etching a pattern into a base material by the photochemical method using a photoresist coating over the base material to enable the exposure of an etching solution to selected portions of the base material wherein the article to be etched is coated with the photoresist material and is thereafter continuously advanced and rotated at relatively uniform rates past a stationary spray of etching solution. A conveying system is also disclosed that is capable of simultaneously rotating and linearly advancing an article. The apparatus comprises a first and second spaced apart conveyor, the movable article carrier therebetween and in engagement with the conveyors and a driving means for each conveyor. The conveyors comprise a driving sprocket, an idler sprocket and an endless carriage in engagement with the sprockets. The endless carriage comprises a core and substantially equally spaced protrusions extending from each side of the core that engage the toothlike configuration of the periphery of each side of the sprockets. The carriages of each conveyor engages the article carrier to provide the linear movement. Differing the linear speeds or direction of travel of the two carriages enables variations in the rotational and linear movement of the article carrier.

2 Claims, 8 Drawing Figures pmmguum 30 ms SHEET 1 BF 3 INVENTORS. JOSEPH F? LAGERMASINJ X LEADO'M A. WARNER ATTO R N EY PATENTEUUET 30 I973 SHEET 2 [IF 3 INVENTORS. JOSEPH P. LAGERMASINI &

LEADOM A. WARNER ATTORNEY PATENTEDBBI30 I975 3.769.111

SHEET 3 OF 3 I VIII/I114 FE E INVENTOR. JOSEPH F! LAGERMASINI 8 BY LEADOM A. WARNER BY WM f ATTORN EY PROCESS AND APPARATUS FOR CHEMICAL MILLING CROSS REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION This invention relates to an improved etching process and to conveying apparatus that is capable of providing dual directional movement to an article being conveyed. More particularly, it relates to an improved etching process wherein an article that is coated with a photoresist is exposed to a more uniform application of etching solution. It also relates to a conveying system that is capable of providing both rotational and linear movement to an article that is conveyed. It further relates to an endless carriage that positively engages driving and idler sprockets and adapted for engagement with an article carrier to provide movement thereto.

Most conveying systems provide unitary directional movement to the article being conveyed. For example, numerous conveyors of the belt, chain and vibratory type provide linear movement to the article being conveyed. Such movement can be in a horizontal or vertical direction on a combination thereof to give an angular movement. In these conveyors primarily linear movement is provided to the article being conveyed. Rotational movement of the articles being conveyed has been normally imparted to the articles while they are notin linear motion. I

Additionally, in many instances, the conveying carriage and the carrier can be subjected to corrosive conditions such as when the article being conveyed is subjected to an etching operation. If the article that is being etched is of a metal nature, there are difficulties in obtaining economical materials of construction that will withstand the corrosive conditions thus eliminating or reducing failures and down time; Materials that are coated or are of a nature oto offer resistance to the materials commonly used as etchants add an appreciable amount of cost to the conveying system.

Chemical millin processes are processes that involve etching of a material particularly in those processes wherein a pattern is selectively etched in a base material using a photoresist coating over the'base material to enable the exposure of an etching solution to a selected portion of the base material. It has generally been recognized that a uniform application of the etching solution over the complete article to be etched yields benefits in processing and quality. Various devices such as rotating sprays, complex arrangements of sprays and the like have heretofore been used to obtain uniformity in the application of the etching solution to the article to be etched. Although these devices have obviated some of the problems of non-uniformity they have not completely solved the problems because of varying pressures and varying spray patterns upon the surface of the coated article. Furthermore, in most instances, the etching action is generally stopped by water tha is applied by sprays. Uniform application is required in order that uniform etching is achieved, therefore, the conveyor can also be used advantageously at the washing step.

Typical conveying mechanisms are generally of either the positively engaging type such as of the chain and sprocket type or of the frictionally engaging type such as flat belt conveyors or V belt driven conveyors. These types of conveyors normally yield only linear movement to the article being conveyed. Other rotational means have to be provided for the desired rotational movement.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of this invention to provide a conveying system capable of imparting simultaneous linear and rotational movement to the article being conveyed.

It is another object of this invention to provide a conveying system that can be structured from materials that are resistant to a corrosive atmosphere.

It is a further object of this invention to provide an improved process for selective etching a base material.

It is believed, therefore, that an invention that achieves the beforementioned objects is an advancement in the art.

In accordance with one aspect of this invention there is provided a conveying system capable of providing linear and rotational movement to an article being conveyed that comprises a first and second conveyor and a movable article carrier for the article being conveyed located inbetween the conveyors and driving means for each conveyor. In accordance with another aspect of this invention, there is provided a unique conveyor that comprises a driving sprocket, an idler sprocket and an endless carriage that comprises a core and substantially equally spaced protrusions extending from opposite side of the core. The article carrier is adapted for engaging the carriages of the first and second conveyors thus enabling the carriages to impart the desired movement to the article carrier. In accordance with an additional aspect of this invention, there is provided an improvement to the process wherein a pattern is selectively etched into a base material by the photochemical method using a photoresist coating over the base material, thereby enabling the exposure of an etching solution to selected portions of the base material. The improvement comprises continuously advancing the article at a relatively uniform rate past a stationary spray of the etching solution while simlutaneously rotating the article at a relatively uniform speed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometrical view of the conveying system of this invention being utilized in an etching process.

FIG. 2 is an elevational view along the line 22 of FIG. 1.

FIG. 3 is a detailed sectional view of one embodiment of the endless carriage of this invention.

FIG. 4 is a detailed sectional view of an alternative embodiment of the endless carriage of this invention.

FIG. 5 is a sectional side view of the driving or idler sprocket.

FIG. 6'is a sectional end view of the driving or idler sprocket.

FIG. 7 is a sectional side view of one embodiment of the article carrier.

FIG. 8 is a sectional end view of the article carrier.

With particular reference to FIG. 1 that illustrates the conveying system of this invention being utilized in a chemical etching operation, the system comprises a first conveyor 10, a second conveyor 12, an article carrier 14, driving means for the first conveyor 16, and a driving means for the second conveyor 18. The first conveyor and the second conveyor 12 are spaced apart with the article carrier 14 therebetween. The first conveyor 10 comprises a driving sprocket to which the driving means 16 is connected, an idler sprocket 22 spaced apart from the driving sprocket 20 and an endless carriage 24 for the first conveyor that passes over both sprockets 20 and 22 of the upper conveyor. The second conveyor 12 is comprised of the same basic components, that is, a driving sprocket 26,. an idler sprocket 28 and an endless carriage 30. The article carrier 14 frictionally engages the endless carriage 24 for the first conveyor 10 and the endless carriage 30 for the second conveyor 12. In the specific embodiment shown an additional idler sprocket 31 is provided as a tensioning device. The first conveyor driving means 16 provides a rotational movement to the upper conveyor carriage 24 which is in frictional engagement with the article carrier 14. The second conveyor 12 operates in a similar manner. The frictional engagement of the two carriages, 24 and 30, with the article carrier 14 provides linear movement thereto. The particular rotation and linear movement of the article carrier 14 will be dependent upon the direction and speed of rotation of the driving sprockets 20 and 26. If the direction of rotation of the driving sprockets 20 and 26 is such that carriages, 24 and 30 move in the same direction rotational movement of the article carrier 14 will depend upon the relative speed of rotation of driving sprockets 24 and 26. If the speed of rotation of 20 and 26 is the same and carriages 24 and 30 move in the same directions no rotational movement is provided. If the direction of rotation of driving sprockets 20 and 26 is such that it imparts movement of carriages 24 and 30 in opposite directions, the direction of rotation and the speed of rotation of the article carrier 14 will depend upon the relative speed of rotation of the driving sprockets. When the carriages 24 and 30 are moving in opposite directions at the same speed only rotational movement will be transmitted to the article carrier 14. In the particular embodiment shown, that is a chemical etching apparatus, an article 32 that has been coated with photoresist material and in a condition for etching is mounted on an article carrier 14 and placed in the conveying system at position A. The article moves to the etching station 34 where stationary sprays (not shown) provide a spray of etching solution in a set pattern upon the article. Etching can be conducted from either side of the article or from both sides simultaneously by procedures well known in the chemical milling art.

During the time the article 32 is in the etching station 34, the article moves linearly and rotates at a speed that is dependent upon the relative speed of linear movement of the two carriages. In some instances, the uniform application that is achieved by the rotational movement is necessary to obtain the desired uniformity of etching that is required by users of some of the products that can be produced by the utilization of this invention. After application of etching solution to the article 32, the pattern 36 is etched and is advanced to position B. The article is removed from the carrier and further treated by procedures well known in the chemical milling art. Although the unique conveying system has been described in relation to utilization in a chemical etching process, it is readily apparent to those skilled in the conveying art that the conveying system can be utilized in various other processes, such as painting, coating or any process where a uniform application of a material capable of being sprayed is to be applied to an article.

With particular reference to FIG. 2, a cross-sectional elevational view of the conveying system illustrated in FIG. 1 taken along line 2--2 of FIG. 1 at the etching station 34 is shown. The etching solution supply headers 38 have sprays 40 that provide a desired spray pattern upon the article 32 that is attached to the article carrier 14. The article carrier 14 is frictionally engaged with the first conveyor carriage 24 and the second conveyor carriage 30. The excess etching solution is collected at the lower portion of the etching station and return through a return header 42 to etching solution storage (not shown). As can be appreciated a water washing station (not shown) can also be provided in series with the etching station.

In particular reference to FIG. 3, one embodiment of i the endless carriage 24 useful in the upper and lower conveyors is shown. The carriage 24 comprises a core 44 and several protrusions 46. Although the cross section of core 44 is shown as being circular, any similar shape such as hexagonal, octagonal, square, oval and the like can be used. Additionally, since the embodiment that is shown is illustrated in respect to chemical milling, the core is shown as plastic such as the various polymeric plastic materials such as the polyethylene, polypropylene polymer, polyvinyl chloride and the like. In the embodiment shown in FIG. 3 the protrusions 46 areprovided by inserting a continuous titanium pin, although other etching solution resistant metals can be used, through the core 44. It is necessary to have protrusions that are substantially equally spaced and on oppositesides of the core for reasons explained hereinafter in reference to the driving sprockets.

With particular reference to FIG. 4, an alternative embodiment is shown wherein the protrusions 46 are of the same material as the core 44. Metals that are resistant to the atmosphere to which the carriage 24 is exposed can be used in place of the plastic shown.

In reference to FIGS. 5 and 6, sections of the driving sprocket 20 are shown. The periphery of each of the side sections 48 and 50 are tooth shaped to receive the protrusions 46 that extend from opposite sides of the substantially the same shape as described.

In reference to FIGS. 7 and 8, sections of an alternative embodiment of the article carrier 14 are shown. The carriage 24 is in positive engagement with the article carrier 14 since the article carrier 14 has a tooth- I said coated article at a uniform rate past a stationary spray of said etching solution while simultaneously rotating said article at a uniform speed.

2. An improvement according to claim 1 wherein said etching solution is applied to said base material in a desired pattern and thereafter providing a spray of water to remove said etching solution at a predetermined distance from said spray of etching solution. 

2. An improvement according to claim 1 wherein said etching solution is applied to said base material in a desired pattern and thereafter providing a spray of water to remove said etching solution at a predetermined distance from said spray of etching solution. 